I decided to switch to Pop!_OS 22.04 from Ubuntu 20.04, while I'm mentally preparing to switch to Devuan in the future. The GRUB is configurable from Ubuntu as expected, but when I do exactly the same thing on Pop!_OS, then suddenly GRUB menu doesn't change at all.
Pop!_OS 22.04 comes with systemd-boot, which I removed via bootctl remove. And then installed grub.
The file /boot/grub/grub.cfg does change after running update-grub, but whether I choose pop or ubuntu from UEFI "boot priority order" menu, it always shows GRUB menu which is configured from Ubuntu (not Pop!_OS).
In /boot/ I have:
grub/grub.cfg
and
efi/EFI/ubuntu/grub.cfg
efi/EFI/pop/grub.cfg
I tried to leave only pop folder (remove ubuntu), but GRUB just shows me its bash-like interface. So I have to reinstall and update GRUB from Ubuntu (chroot from live CD), since doing this from Pop!_OS doesn't affect anything (for the end user).
I'm using Lenovo Yoga 920-13IKB laptop.